<template>
 <div class="container">
  <div class="layout">
   <button
    class="layout-btn"
    @click="layoutType=val.value"
    v-for="val in layoutOptions"
    :key="val.value"
   >{{val.label}}</button>
  </div>

  <div
   class="group"
   :class="{'left-top-container': gindex===0,
    'right-top-container': gindex===1,
    'bottom-container': gindex===2,
    'top-container': gindex<2}"
   v-for="(group,gindex) in data"
   :key="gindex"
  >
   <div
    class="cls-default"
    v-for="(item,cindex) in group.children"
    :key="cindex"
    :data-id="gindex+'-'+cindex"
    draggable="true"
    @dragstart="onDragstart($event)"
    @dragend="onDragend($event)"
    @dragover="onDragover($event)"
    @drop="onDrop($event)"
    :
    :class="{'cls1-0': cindex ===0 && layoutType==1,
    'cls2-0': (cindex ===0 || cindex ===1) && layoutType==2,
    'cls3-0': cindex ===0 && layoutType==3,
    'cls3-1': (cindex ===1 || cindex ===2) && layoutType==3,
    'cls4-0': cindex <4 && layoutType==4,
    'cls6-0': cindex === 0 && layoutType==6
    }"
   >
    <div class="content">{{item.color &#63; item.color : '我是空對象'}}</div>
   </div>
  </div>
  <div class="tips">上面兩個區域內是展示區的內容能互相拖拽
   <br>下面的是資源區，只能復制出去覆蓋目標區域，本身不會被替換掉
  </div>
 </div>
</template>

<script>
export default {
 data() {
  return {
   stargindex: "",
   endIndex: "",
   layoutType: "9",
   layoutOptions: [
    { label: "單分屏", value: 1 },
    { label: "二分屏", value: 2 },
    { label: "三分屏", value: 3 },
    { label: "四分屏", value: 4 },
    { label: "六分屏", value: 6 },
    { label: "九分屏", value: 9 }
   ],
   data: [
    {
     group: "left-show",
     title: "視頻播放區一",
     children: [
      {
       id: 6,
       color: "orange"
      },
      {
       id: 2,
       color: "yellow"
      },
      {},
      {},
      {},
      {},
      {
       id: 3,
       color: "cyan"
      },
      {},
      {
       id: 5,
       color: "brown"
      }
     ]
    },
    {
     group: "right-show",
     title: "視頻播放區二",
     children: [
      {},
      {
       id: 7,
       color: "pink"
      },
      {},
      {},
      { id: 4, color: "purple" },
      {},
      {},
      {},
      {
       id: 10,
       color: "gray"
      }
     ]
    },
    {
     group: "source",
     title: "視頻資源區",
     children: [
      {
       id: 11,
       color: "white"
      },
      {
       id: 12,
       color: "black"
      },
      {
       id: 13,
       color: "red"
      },
      {
       id: 14,
       color: "green"
      },
      {
       id: 15,
       color: "blue"
      }
     ]
    }
   ]
  };
 },
 methods: {
  onDragstart(event) {
   this.stargindex = event.target.getAttribute("data-id");
  },
  onDragend(event) {
   let startGroupIndex = this.stargindex.split("-")[0];
   let startChildIndex = this.stargindex.split("-")[1];
   let endGroupIndex = this.endIndex.split("-")[0];
   let endChildIndex = this.endIndex.split("-")[1];
   // 對數據做簡單的深拷貝 目前不需要
   // let endObj = JSON.parse(
   //  JSON.stringify(this.data[endGroupIndex].children[endChildIndex])
   // );
   // let startObj = JSON.parse(
   //  JSON.stringify(this.data[startGroupIndex].children[startChildIndex])
   // );
   let endObj = this.data[endGroupIndex].children[endChildIndex];
   let startObj = this.data[startGroupIndex].children[startChildIndex];
   if (this.data[endGroupIndex].group === "source") {
    //往資源區拖拽時 不做任何替換操作
    return;
   }
   this.data[endGroupIndex].children.splice(endChildIndex, 1, startObj);
   if (this.data[startGroupIndex].group !== "source") {
    //拖拽起始區域不是 source時 把起始區域替換成拖拽后區域的數據
    this.data[startGroupIndex].children.splice(startChildIndex, 1, endObj);
   }
  },
  onDrop(event) {
   if (event.target.className.indexOf("cls-default") > -1) {
    this.endIndex = event.target.getAttribute("data-id");
   } else {
    this.endIndex = event.target.parentElement.getAttribute("data-id");
   }
  },
  onDragover(event) {
   event.preventDefault();
  }
 }
};
</script>

<style scoped>
.container {
 background-color: #eee;
 height: 800px;
}
.layout .layout-btn {
 background-color: #409eff;
 color: #fff;
 padding: 10px 15px;
 margin: 10px 15px;
}
.tips {
 font-size: 24px;
 text-align: center;
}
.group {
 float: left;
 overflow: hidden;
 box-sizing: border-box;
}
.group-title {
 height: 40px;
 line-height: 40px;
}
.cls-default {
 float: left;
 margin: 0;
 box-sizing: border-box;
 overflow: hidden;
 border: 1px solid #999;
}
.cls-default .content {
 text-align: center;
 padding-top: 20px;
 font-size: 20px;
}
.top-container {
 height: 400px;
 width: 40%;
 margin: 15px 5%;
}
.top-container .cls-default {
 width: 33.33%;
 height: 33.33%;
}
.top-container .cls1-0 {
 width: 100%;
 height: 100%;
}
.top-container .cls2-0 {
 width: 50%;
 height: 100%;
}
.top-container .cls3-0 {
 width: 50%;
 height: 100%;
}
.top-container .cls3-1 {
 width: 50%;
 height: 50%;
}
.top-container .cls4-0 {
 width: 50%;
 height: 50%;
}
.top-container .cls6-0 {
 width: 66.66%;
 height: 66.65%;
}
.bottom-container {
 width: 90%;
 height: 200px;
 margin: 15px 5%;
}
.bottom-container .cls-default {
 width: 15%;
 height: 150px;
}
</style>